Early reports painted the two as misfits, members of a campus Trenchcoat Mafia, dark and brooding. Now, 14 days after the deadliest school shooting in US history, the portrait that has emerged is fuller - including participation in all-American activities such as Little League and Boy Scouts - but it is no less confounding.

Perhaps most puzzling is the degree to which the boys were able to maintain a faade of normalcy - holding down jobs at a local pizza shop, attending classes - all the while covertly obtaining guns, building pipe bombs, and plotting mass murder.

At the very least, this tragedy in suburban Denver may indicate how closely parents need to watch for signs of trouble in their teenagers.

"Teenagers are fantastic at hiding things from their parents," said Edgar Berg, a geophysicist who once worked with Dylan's father, Tom Klebold. "The more I talk with people who know Tom, the more baffling it becomes." He adds: "This is not a negligent parent."

By most accounts, Eric and Dylan had become disconnected from their fellow students - and many of their classmates noticed it. In earlier times, Dylan played baseball, and according to published reports, he was a pitcher who threw the ball as hard as anyone else, and hated to lose.

Eric had played soccer, left forward and mid-field, says Columbine senior and former soccer teammate Josh Swanson. He was not a star, but he was solid, and Josh recalls seeing Eric's parents standing on the sidelines during games.

But all this changed, and athletes became a nemesis for the two. Josh first noticed the change in Eric during junior year. Eric started wearing all black and T-shirts with German writing - although fellow students said his fascination with things German dated back to freshman language classes.

That's also when Eric began hanging out with the school's so-called Trenchcoat Mafia, a clique known for the black trench coats members wore no matter the weather. According to various reports, members listen to dark, industrial music by singers such as KMFDM. They wear swastikas. They also despise the "jocks," athletes who dominate school social life.

And the jocks expressed their animosity too, referring to the trench coats as "dresses" and even lobbing bottles at group members, according to one account.

"It's the same old story," Josh said the day after the shootings, as he stood by a budding memorial of flowers and notes. "The jocks tease the smokers."

Josh and others have suggested that it may have been the desire for friends that prompted Eric to join the trenchcoat group. Although Eric sometimes seemed "aggravated," Josh says, "the Trenchcoat Mafia accepted a lot of different people. They were probably the most accepting people."

Eric was born in Wichita, Kan., to Air Force transport pilot Wayne Harris and his wife, Kathy. The family moved around the country before landing in Colorado. Those who knew the Harris family talked of Eric's fishing derbies in Michigan, Little League in New York, and soccer in Littleton.

Dylan's family lives in a home dramatically tucked inside red-rock outcroppings, where his father operates a mortgage business. Sue Klebold works to improve access for the disabled for the community-college system. Dylan's father is Lutheran, and the family visited with a Lutheran pastor. His mother is Jewish, and the family observed Passover.

According to various accounts, Tom Klebold has described Dylan and older brother, Byron, as his best friends, and was involved in Dylan's life. In a phone interview, Mr. Berg speculated that the only guns in the house would have been those Dylan hid from his parents, given Tom Klebold's antigun views.

"This kid had some major compartments going on," he says.

If the boys' parents failed to recognize their sons on the day of the Columbine High massacre, so did plenty of others. A supervisor at Blackjack pizza delivery, where Eric and Dylan appeared for their cooking jobs on time and in uniform (black pants and red polo shirts with the store logo), has described them as "the best two" employees, not counting delivery people.

LIKEWISE, a run-in with the law last year - in which Dylan and Eric were arrested for breaking into a car and stealing $400 worth of tools and electronic equipment - ended with high praise for the boys. Because it was their first arrest, they entered a district attorney's office juvenile diversion program.

According to reports written at the time they were released from the program, "Eric is a bright young man who is likely to succeed in life," and "Dylan is a bright young man who has a great deal of potential."

In addition to the arrest, there were some other red flags, but no one person or central agency paid close enough heed to see where they were leading.

Some classmates remember the two boys walking down the halls sneering, and sensed anger just under the surface.

But it's in the electronic world of the Internet and video games - and in a diary kept by Eric - that the dark impulses of the boys may have been most evident.

Perhaps most notably, Randy and Judy Brown had some proof. They found a Web site Eric had created, in which he allegedly threatened to kill their son, Columbine student Brooks Brown, and others. The Browns downloaded 18 pages of violent screed, and turned it over to the county sheriff's department.

"I am the law, if you don't like it, you die...." the pages read. "I can't wait until I can kill you people."

One newspaper account indicates that a police report on the Web site was forwarded to the deputy stationed at Columbine High, who is reported to have talked at least once with the boys.

Presumably, it's Eric's diary, which has not been made public, that tells how the plot evolved and when the lethal weapons were obtained. Officials have said it details a year-long plot to kill fellow students and destroy the school on April 20, Hitler's birthday.

Officials have also said that another Columbine student, a girl who went to the prom with Dylan just three days before the rampage, obtained three of the four guns the pair used. Police are investigating whether a co-worker at the pizza shop helped them buy the fourth, a Tec-DC9 assault pistol.

Then there's the most recent rejection.

Five days before the shooting, Eric learned he was disqualified for service in the US Marines for taking the prescription drug Luvox, used to treat depression and obsessive-compulsive disorder. The New York Times reported that Eric may have stopped taking the drug before the school shooting because he knew it was grounds for dismissal from the Marines.